LASER INDUCED FLUORESCENCE SPECTROSCOPY IN COMBUSTION STUDIES

Author Institution:Of the several laser spectroscopic probe techniques recently developed for studying combustion processes, laser-induced fluorescence (LIF) is the one especially suited for the detection of transient species present at low concentration. These molecules, often free radicals, play a paramount role in the reaction networks of flames, and their measurement is thus important in developing an understanding of combustion chemistry. To date, about twenty such species have been observed using LIF in flow systems and/or in flames; of these, the ubiquitous OH molecule is by far the most popular. This overview will consider some of the flame experiments from the standpoints both of combustion research needs and the spectroscopy involved. The problems, and various remedies, in accounting for the influence of collisional energy transfer and quenching on the observed LIF signals will be discussed. Finally, some ramifications of LIF--optogalvanic effects, optoacoustic effects, and multiphoton excitation in flames--will be briefly treated